Decrypted mail blank in mail client

Hi Michael,

The most likely reason you cannot red the email is that the email was
first opaquely signed and then encrypted (probably by Outlook).

CipherMail removes the encryption but keeps the signed email. If the
email was opaquely signed (which is the default with Outlook when the
email is encrypted), you need an mail client which can handle opaquely
signed email. If you email client cannot handle opaquely signed email,
your best option for now is to have the gateway remove the signature
(see settings).

For a recent discussion about a similar issue see

I will spend some time investigating two options: is it possible to
convert an opaquely signed email to a clear signed email without
breaking the signature or, add an option to only remove the signature
if the email is opaquely signed

Kind regards,

Martijn Brinkers


CipherMail email encryption
Email encryption with support for S/MIME,
OpenPGP, PDF Messenger and Webmail Messenger

On Wed, 2021-03-17 at 17:01 +0000, Prof. Dr. Michael Schefczyk via Users wrote:

Dear All,

For SOHO purposes, I have been using a chiphermail gateway for a long
time, traditionally in front of an Exchange server. Recently, I did
swich to Kopano - please feel free to guess why.

There was one problem with decytped mails that annoyed me with
Exchange but that is more critical with Kopano and I am unable to
describe it adequately to Kopano. It might have to do with opaque
signing or it might have other reasons.

When I receive an SMIME-encrypted e-mail, the gateway does decrypt
it. With Exchchange, the behavior was:
- decrypted message was fully visible in outlook - one could work
with it just as expected
- on Android (LineageOS, standard mail client), the decrypted message
was marked as encrypted and not presentable despite the fact that it
was in fact decrypted.
I found that annoying, but I could stand that. If needed, I did use

With Kopano, the behavior is:
- decrypted message is shown blank in Kopano client. When downloading
in .eml format, it can be viewed (with Outlook, for example)
- on Android, the decrypted message is also shown blank. Just an
smime.p7m enclosure is visible.

I would very much welcome, if Martijn or someone else could point me
to the right direction to resolve this issue. Any help in describing
the issue to Kopano and/or in understanding which features might have
to be enabled in php and/or apache in use would be great.

Thanks & Regards,

Technische Universität Dresden
Fakultät Wirtschaftswissenschaften
Lehrstuhl für Entrepreneurship und Innovation
Prof. Dr. Michael Schefczyk
D-01062 Dresden

Fon: +49-3 51-4 63-3 68 81
Fax: +49-3 51-4 63-3 68 83